A systematic review of genome-wide analyses of methylation changes associated with assisted reproductive technologies in various tissues
Tania L. Gonzalez, Muhammad Hamza Khan, Erica T. Wang
Jessica L. Chan, Margareta D Pisarska, Amelia M. Schaub , Anna E. Dorfman , Allynson G. Novoa , Rimsha A. Hussaini , Paige M. Harakuni , Brandon J. Shabani , Akhila Swarna , Williams J 3rd , John Williams
Because analytic technologies improve, increasing amounts of data on methylation differences between assisted reproductive technology (ART) and unassisted conceptions are available. However, various studies use different tissue types and different populations in their analyses, making data comparison and integration difficult.
Objective
To compare and integrate data on genome-wide analyses of methylation differences due to ART, allowing exposure of overarching themes.
Evidence Review
All studies undertaking genome-wide analysis of human methylation differences due to ART or infertility in any tissue type across the lifespan were assessed for inclusion.
Findings
Seventeen studies were identified that met the inclusion criteria. One study assessed trophectoderm biopsies, 2 first-trimester placenta, 1 first-trimester fetal tissue, 2 term placenta, 7 cord blood, 3 newborn dried blood spots, 1 childhood buccal smears, 1 childhood peripheral blood, and 2 adult peripheral blood. Eleven studies compared tissues from in vitro fertilization (IVF) conceptions with those of unassisted conceptions, 4 compared intracytoplasmic sperm injection with unassisted conceptions, 4 compared non-IVF fertility treatment (NIFT) with unassisted conceptions, 4 compared NIFT with IVF, and 5 compared an infertile population (conceiving via various methods) with an unassisted presumably fertile population. In studies assessing placental tissue, 1 gene with potential methylation changes due to IVF when compared with unassisted conceptions was identified by 2 studies. In blood, 11 potential genes with methylation changes due to IVF compared with unassisted conceptions were identified by 2 studies, 1 of which was identified by 3 studies. Three potentially affected genes were identified by 2 studies involving blood between intracytoplasmic sperm injection and unassisted populations. There were no overlapping genes identified in any tissue type between NIFT and unassisted populations, between NIFT and IVF, or the infertility combined population when compared with the unassisted fertile population.
Conclusions
Comparing studies is challenging due to differing variables between analyses. However, even in similar tissue types and populations, overlapping methylation changes are limited, suggesting that differences due to ART are minimal.
RELEVANCE: Information from this systematic review is significant for providers and patients who provide and use ART to understand methylation risks that may be associated with the technology.
The number of sperm that reaches the oocytes in mammalian species is limited. In mice, 8-10 oocytes are ovulated, a similar number of sperm reaches the oocytes, and nearly all oocytes are fertilized via natural mating. Meanwhile, our improved superovulation technique (ultrasuperovulation: administration of inhibin antiserum and equine chorionic gonadotropin [IASe]) produced 100 oocytes from a single female C57BL/6 mouse but resulted in only approximately 20 fertilized oocytes via mating. We hypothesized that sperm shortage in the ampulla might cause this low fertilization rate. Mice were mated in the proestrus stage or after hormone injection, but ovulation timing was not considered. In clinical application, the rhythm method supports fertilization by testing the ovulation period and synchronizing the ovulation and copulation timings. Therefore, this study examined the effects of ovulation and copulation timings on in vivo fertilization in female mice with IASe. Synchronization of the ovulation and copulation timings increased fertilization efficiency in female mice with ultrasuperovulation. The number of embryos obtained post ovulation was three times higher than that obtained pre ovulation. This study suggests that synchronized ovulation and copulation timings improve the efficiency of in vivo fertilization in IASe-treated female mice. This technique can be used to produce genetically modified mice and develop technologies for infertility treatment.
Sanders JN et al., 2016·Paediatr Perinat Epidemiol
Most cohort-based research for subfertility has been conducted in clinic-based cohorts, which may differ from population-based cohorts. We retrospectively recruited parallel one by sampling two specialty fertility clinics in Utah, and one by population-based sampling based on marriage and birth records. The index date (of first clinic visit or subfertility status) was between 2000 and 2009, and we linked the women recruited to subsequent birth certificate records through December 2010. We enrolled 459 women through clinic-based sampling and 501 women through population-based sampling. Clinic-based women were older, had higher annual household income and more likely to have had a most intensive treatment of intrauterine insemination (31%) or in vitro fertilisation (46%) than women from population recruitment (19% and 14% respectively). Conversely, they were less likely to have received no medical treatment (9%) compared to women from population recruitment (41%). For both types of sampling, prior to eligibility screening, non-responders were less likely to link to a 51% vs. 58% for clinic-based, and 69% vs. 76% for the population-based with an index date in 2004. Population-based sampling for subfertility cohort research identifies women who were more likely to have had less intensive treatment or no treatment. However, in both clinic-based and population-based sampling, women who have had a live birth are more likely to respond to retrospective recruitment.
Many women throughout the world have history of subfertility (resolved or unresolved), but much remains unknown about services and treatments chosen. We developed a mixed-mode fertility experiences questionnaire (FEQ) in 2009 through literature review and iterative pilot work to optimize question format and mode of administration. The focus of the FEQ is to collect data retrospectively on time at risk for pregnancy, fertility treatments received and declined, pregnancy, time to pregnancy and pregnancy outcomes. We conducted a validation of key elements of the FEQ with comparison to medical records in 2009 and 2010. The validation sample was selected from women initially seen at a specialized fertility treatment center in Utah in 2004. The FEQ was 1) written (paper or web-based), self-administered, followed by 2) telephoneadministered questions. In 63 patients analyzed, high levels of correlation were identified between patient self-report and medical records for the use of intrauterine insemination and assisted reproductive technology, pregnancy and live birth histories, time at risk for pregnancy and time to pregnancy. There was low correlation between medical records and self-report for the use of oral ovulation drugs and injectable ovulation drugs. Compared to the medical record, the FEQ was over 90% sensitive for all elements, except injectable ovulation drugs (70% sensitivity). The FEQ accurately captured elements of fertility treatment history at 5-6 years after the first visit to a specialty clinic.
Schisterman EF et al., 2013·Paediatr Perinat Epidemiol
Low-dose aspirin (LDA) has been proposed to improve pregnancy outcomes in couples experiencing recurrent pregnancy loss. However, results from studies of LDA on pregnancy outcomes have been inconsistent, perhaps because most studies evaluated LDA-initiated post-conception. The purpose of the Effects of Aspirin in Gestation and Reproduction (EAGeR) trial was to determine whether preconception-initiated LDA improves livebirth rates in women with one to two prior losses. We performed a multicentre, block randomised, double-blind, placebo-controlled trial. Study participants were recruited using community-based advertisements and physician referral to four university medical centres in the US (2006-12). Eligible women were aged 18-40 years actively trying to conceive, with one to two prior losses. Participants were randomised to receive daily LDA (81 mg/day) or a matching placebo, and all were provided with daily 400-mcg folic acid. Follow-up continued for ≤6 menstrual cycles while attempting to conceive. For those who conceived, treatment was continued until 36 weeks gestation. The primary outcome was the cumulative livebirth rate over the trial period. There were 1228 women randomised (615 LDA, 613 placebo). Participants had a mean age of 28.7, were mostly white (95%), well educated (86% more than high school education), and employed (75%) with a household income >$100 000 annually (40%). The characteristics of those in the treatment and placebo arms were well balanced. We describe the study design, recruitment, data collection, and baseline characteristics of participants enrolled in EAGeR, which aimed to determine the effect of LDA on livebirth and other pregnancy outcomes in these women.